Gas operated machine gun and automatic small arm



June 23, 1931. A. LARSSON ET AL 9 5 GAS OPERATED MACHINE GUN ANDAUTOMATIC SMALL ARM Filed Jan. 13, 1931 Patented June 23, 1931 NIT DSTATES PATENT oFFrcs CARL ALFRED LARTSSONv AND PERCY REUBEN .HIGSON, OFWESTMINSTER, ENGLAND,

.ASSIG'NORS TO VIGKERS-ARMSTRONGS LIMITED; OF WESTMINSTER,

BRITISH COMPANY ENGLAND, A

GAS OPERATED MACHINE -GUN,.AND AUTOMATIC SMALL ARM [Application filedJanuary 13, 1931, Serial No. 508,492, and in Great Britain February 10,1930.

This invention relates to machine guns with the bore of the barrelthrough a port in the latter. This plug has heretofore been made in onepiece and the passages have necessarily been of straight formation withone portion generally at right angles to the other, with the result thatthey are liable to become blocked with solid fouling matter contained inthe gases of combustion from the bore of the barrel.

According to the present invention the gas plug is made in two parts,viz., a main part which is adapted to be secured in the block and asubsidiary part which fits into the main part and is provided with acurved gas-passage in the form of a recess opening on to one of thefaces of this subsidiary part. When the plug is in position in the blockthe upper end of the said recess communicates with a port in the blockleading to the port in the barrel and the lower end of this passagecommunicates with the portion of the block to which the operatingcylinder is attached.

'- The said subsidiary part is preferably of flat formation and isdisposed within a slot formed in the main part of the plug. It will beunderstood that when the subsidiary part is in position in the main partthe gas passage is constituted by the three walls of the recess in thesubsidiary part and by the eontiguous wall of the slot in the main part.

In order that the said invention may be clearly understood and readilycarried into effect, the'same will now be described more fully withreference to the accompanying drawings, in which Figure 1 is a verticalsection showing a con 1 structional form of composite gas plug accordingto this invention in position in a gas block carried by the gun barrel.

Figure 2 is a horizontal section of the gas block taken approximately onthe line 2, 2 of Figure 1, the gas plug not being shown in section,

Figure 3, is a side view of the main part of the gas plug removed fromthe gas block, Figure 4 is an end view of Figure '3,

Figure '5 is .a vertical section of Figure 3, I

. Figures '6 and 7 are horizontal sections taken approximately on thelines 6, 6 and 7, 7 respectively of Figure 8,

Figure 8 is a side elevation of the subsidiary part of the gas plugremoved from the main part, V

Figure 9 is a vertical longitudinal section of the said subsidiary part,

Figure 10 is a plan of Figure 8, and

Figure 11 is a horizontal section taken approximately on the line 11, 11of Figure 8. A is the gas block the upper portion of which is in theform of a sleeve to surround the gun barrel 1 and the lower part has arecess to receive the gas plug. This recess terminates at its upper endin a port A which registers with a port 2 formed in the gun barrel andat its left hand side, as drawn in Figure 1, the said recesscommunicates with the bore of the spigot portion A which fits into theoperating cylinder 3 for the breech mechanism. The said gas block issimilar in its essentials to that described in prior Englishspecification No. 252,429.

The gas plug is, as aforesaid, composed of two parts, .v1z a main part Band a subsidiary part C. The said main part, which is adapted to bescrewed-into the recess in the block A, is formed with a diametricalslot B The subsidiary part C is flat and constructed to fit closelywithin the slot B it is formed on one of its faces withra curved recessC one end of which terminates on its upper surface and the other endterminates of the curved recess C and by the. contiguous wall of theslot B The said curved recess can conveniently be made by a millingoperation.

The main part B of the gas plug is shown as being formed with recesses BB for purposes similar to those of the corresponding recesses in the gasplug described in our aforesaid prior specification and the block A isformed with a hole A for the reception of the customary regulating valveB (shown in broken lines in Figure 2) to control the amount of gas to beadmitted to the operating cylinder. A portion of the gases reaches thisregulating valve by means of arecess B in the portion of the main part Bbetween the recesses B E the shape of the recess B being shown in Figure6. The rear portion of the subsidiary part C is cut away (at C tocoincide with the recess 13*. The portion of the part C on which thelower end of the curved recess C terminates, coincides with the portionof the main part B between the recesses B B and the part C is cut away(at C above the portion thereof above referred to so as to coincide withthe recess B part C has a sloping base and the bottom of the slot B inthe part B is similarly formed so as to ensure that the part C is placed111 the slot the correct way round. It will be understood that the partC is held in position within the part B by its contact with the wall ofthe recess in the block A.

What we claim and desire to secure by Letters Patent of the UnitedStates is':

1. For use in the gas block of a machine gun or automatic small arm ofthe gas operated type, a gas plug composed of a main part which isadapted to be secured in the gas block, and a subsidiary part which fitsinto the main part and is provided with a curved gas passage in the formof a recess into said slot and is provided with a curved I recessopening on to one of the faces of said subsidiary part, the gas passagebeing constituted by the three walls of the curvedrecess in thesubsidiary part and by the contiguous wall of the slot in the main part.

3. For use in a machine gun or automatic small arm of the gas operatedtype, the combination with the gas block, of a gas plug composed of amain part-, means for securing said part in the gas block, and asubsidiary part which fits into the main part and is provided with acurved gas passage in the form of a recess opening on to one of thefaces of said subsidiary part.

4. For use in a machine gun or automatic The 1 the contiguous wall ofthe slot in the main CARL ALFRED LARSSON. PERCY REUBEN HIGSON.

part.

